There are many types of cutting systems used to destroy documents and other sensitive materials. These cutting systems may include, for example, shredders, pulverizers, grinders and other cutting systems. Existing document-destruction machines are intricate, complex, and delicate. This poses a problem in high security applications, such as highly sensitive or classified government documents that need to be easily and efficiently destroyed for various security or business reasons. Also, many of the known cutting systems are prone to wear, failure and other problems which require constant maintenance and/or refurbishment. The maintenance and/or refurbishment of these complex systems, of course, requires considerable “down-time” which, in turn, also adds to the overall costs of the system. An additional shortcoming of many of these systems is their single use nature, i.e., only capable of shredding, for instance, paper.
By way of example, U.S. Pat. No. 5,340,034 to Jang shows a paper grinder. In this system, a paper document is capable of being ground to a powder form; however, this system uses both a complex arrangement consisting of a corrugation system and an impacting or pulverizing system. In this system, if one of the components fails, for example, the corrugation system, then the document cannot be pulverized. This may result in a significant security risk. It is further noted that this system includes a complex array of rollers and cutters in order to perform the dual purpose of corrugation and pulverizing. This may lead to additional (i) component failure, (ii) maintenance and (iii) downtime, thereby increasing the cost of the entire system. Also, in the pulverizing step, it is necessary to repeatedly pulverize the material over an extended time period in order to achieve the powder form, thus resulting in a disadvantage of the system. It is lastly noted that this system appears to be capable of performing its functions only on paper products, but not other materials which may also need to be destroyed. This is a limiting feature of the Jang apparatus.
In another example, U.S. Pat. No. 6,079,645 to Henreckson shows a desktop shredder. In this shredder, a shredding knife simply shreds paper; however, this system does not and, in fact, appears to be incapable of completely shredding paper into an information-unrecoverable product. Instead, the paper is merely cut into strips. Also, this same system seems applicable only to paper products, thus limiting its applicability to other products (such as polyester (“Mylar”) tape) which require shredding or destruction. See, also U.S. Pat. No. 5,975,445 to Ko. Similarly, U.S. Pat. No. 5,320,287 to Li also shows a paper shredder which is provided for the limited use on paper, and which also is incapable of providing an information-unrecoverable product. In fact, Li only discloses that the paper may be shredded into smaller pieces than “strip” shredders.
Of course other materials may also be destroyed for high security purposes. These materials may be, for example, Mylar or other thin films that carry printed, punched, magnetically recorded, optically recorded, or otherwise recorded information. Such materials may also need to be destroyed in a high security fashion. Conventionally, this could heretofore only be performed by certain, specially-qualified high-security document “disintegrators”, which are heavy (several hundred pounds), expensive, power-hungry, and very noisy. Conventional shredding machines, including “disintegrators”, tend to jam with certain materials (like Mylar), which tend to stretch and spindle, rather than be cut properly by the shredding or “disintegrating” apparatus. As indicated at http://www.sdiasac.com/NDSdest.doc, the U.S. National Security Agency (NSA) has evaluated certain conventional equipment as meeting, or not meeting, the requirements for routine destruction of classified and sensitive material, including high tensile strength paper tape, paper mylar-paper tape and plastic key tape as mentioned above.
Existing “high-security disintegrators” have the further disadvantage of limited effectiveness, in that the current Department of Defense standard for such machines specifies a 3/32″ output screen. This means that a particle as large as 3/32″ on a side may pass through the disintegrator and still meet the destruction standard. In many cases, a particle of this size may carry a considerable amount of recoverable optical or digital information.
Such films or film-containing papers could, of course, be destroyed by incineration, but this method is undesirable for reasons of health (toxic fumes from burning), safety, convenience, and secrecy.
Acceptable standards for high-security destruction of paper and other products are being redefined to demand destruction into smaller-size particles. An unmet need remains for machines, devices, methods and systems by which to completely destroy to-be-destroyed materials, while providing ease, reliability and simplicity.
Scissoring is a cutting mechanism that has been conventionally applied to paper destruction, albeit with limitations. The limitations of conventional scissoring may be appreciated by considering a simple pair of hand-held scissors. Spring loading pushes one blade against the other blade. The blades are not completely straight, but are intentionally curved with a slight bow, sometimes with one blade bowed more than the other blade. As the scissors close, the structure is forcibly uncurved, which is how zero-clearance is conventionally achieved by spring loading in scissoring technology. Initially, when the scissors are new, at contact there are two sharp edges, which is what is wanted for cutting action. However, eventually the sharp edges get worn off, blunted, and ground away. Eventually at the traveling point of contact, blunting and voids in the edges occur, and clearance rather than zero-clearance occurs.
Certain conventional rotary shears have been attempted, to provide conventional shredders. A disk of tooled steel is notched. When that notched disk wipes past another part, cutting happens. However, if there is any clearance, a to-be-cut material does not get cut, but rather, goes between the cutting edges. Such an apparatus gets dull because the action of parts rubbing against each other wears away the material of each. When the parts are dull, the assembly must be taken apart and the head replaced. Zero-tolerance between parts can be kept by using spring-loading but such an arrangement is not actually cutting but rather is bludgeoning and takes more power than cutting.
To get a cross-cut operation, complex helical shapes are needed, and certain shapes have been used conventionally. Helically-fluted is the best of such conventional technology. Non-helically fluted shapes do not provide the cross-cut, but only the strip-cut. Strip-cutting cannot reduce the output to a size as small as desired, because the there is a limit to how thin the cutters can be made, which in turn limits how thin the resulting strips can be. Cross-cutting is needed to get smaller output.
A multiple-head (three-head) conventional cross-cutting destruction device is in use for high-security paper shredding. However, that device has these limitations (among others): 1) Multiple heads are needed to sequentially re-shred the material. This requires a costly and complex machine. 2) Even with multiple heads, the shredding cutter elements must be tightly spaced and thin, to get small-sized output. The cutting elements must therefore be somewhat delicate, which leads to shorter overall cutter life, greatly reduced reliability, and greatly increased susceptibility to damage from the introduction of staples, paper clips, etc. into the shredding process along with the paper. This is a problem for all high-security shredders, and the finer the output, the greater the problem. 3) Even with multiple heads, there is a possibility of oversized particles getting past all of the heads.
The conventional thinking has been that, as a practical matter, the output can be gotten only so small, from a length×width perspective, because of design and manufacturing limitations. Namely, the conventional three-head device used multiple fluted rotating, meshing cylindrical parts with scissoring action, with a precision fit established between scissoring parts. Strips with length and width dimensions are the output of the operation of the two fluted rotating, meshing cylindrical parts. The strip is then permitted to drop down, into a second set of the same arrangement of two fluted rotating, meshing cylindrical parts with scissoring action. Such conventional scissoring action, multi-head machines suffer from inherent limitations both through machining tolerances and through the impossibility, at a certain point even if a smaller parts can be made, of providing support for the reduced-size parts, and providing force to shred the paper without bending or breaking the delicate shredder parts.
Adding to the concerns and problems discussed above for paper and paper-like products, there is further considered the problems, perhaps even more technically complex, of destroying information stored on or in other media besides paper. For example, there is a need to be able to completely, reliably and easily destroy other kinds of information-bearing media, such as photographs, photo negatives, compact disks, credit cards, data cards, so-called “smart” cards (containing electronic data storage circuits as well as magnetic and optical data), plastic film, cassette tapes, magnetic tape, etc.
By way of further background, others' conventional shredders (if they are any good for high-security shredding) use oil applied to the cutting elements, sometimes with automatic oilers. Without oil, they slow down and have reduced life. (Disintegrators do not use oil in cutting, as oil would foul the screen in the disintegrator.) Both shredders and disintegrators use grease and/or oil for their gears, chains, bushings, bearings, pivots, etc.